Posture control of one-link torque unit manipulator using reaction wheel with air resistance

In this research, we study on posture control of a planar one-link torque unit manipulator which has a revolute joint with viscous friction. The torque unit is a module that consists of an electric motor and a reaction wheel, and it can be set to an arbitrary position of the link as an actuator to control the rotating link with free joint. However, the system has an uncontrollable mode. There arises a problem such that angular momentum remains in the reaction wheel of the torque unit after controlling to a desired posture. In this report, we consider using a reaction wheel with air resistance. Then we show that the link can be controlled to a desired posture with avoiding the problem mentioned above even though the system has an uncontrollable mode.